How to Control Horsenettle in Hayfields and Pastures

By Blake Jackson

At this year’s Ag Progress Days, one of the most common questions asked by farmers was how to deal with horsenettle in hayfields and pastures. The combination of a wet spring and dry summer has favored this troublesome weed, making it a challenge in grass forages.

Horsenettle, a warm season creeping perennial native to the United States, is highly persistent. It begins active growth in May and continues until early fall, spreading through both seeds and shoots that emerge from its deep roots.

Its ability to tolerate drought, poor soils, and hot conditions allows it to thrive in many environments, especially overgrazed pastures. While frost kills its aboveground growth, the roots survive and fuel regrowth the following season.

Beyond reducing forage quality, horsenettle poses risks to livestock. Its sharp spines can injure mouths and throats, and it contains toxic compounds that vary in concentration depending on conditions.

Unripe green berries are particularly dangerous, but the entire plant can be poisonous, even in hay. Solanine, the toxic alkaloid, remains active after drying. Cattle are most at risk if desirable forage is limited, though well-fed animals typically avoid it.

Managing horsenettle requires a combination of approaches. Good agronomic practices such as maintaining proper soil fertility, managing grazing pressure, and keeping field edges clean form the foundation. Mowing can weaken plants, but on its own is rarely effective.

Ideally, mow once or twice a season, then allow regrowth to about a foot tall and flowering before applying herbicides in midsummer to early fall.

Effectiveness depends on both the product and the field type. In hayfields, Crossbow (3-4 quarts/acre) can achieve about 80% control. In permanent pastures, GrazonNext HL (1.5-2.6 pints/acre) is more effective, reaching roughly 85% control.

Other options, such as 2,4-D, dicamba, or metsulfuron, provide about 70% control but only temporary suppression. Herbicide timing is key applications late in the season may fail if insect feeding damages leaves or if plants start going dormant.

Always follow grazing and haying restrictions on product labels, as waiting periods vary depending on the herbicide and livestock type. For detailed recommendations, refer to the 2025 Penn State Agronomy Guide.

Photo Credit: gettyimages-jacqueline-nix